text: The international anti-corruption summit - the first of its kind - is aimed at exposing, punishing and drive out global corruption.
  Political leaders, businesses, sporting organisations, and charities will meet at Lancaster House on Thursday.
  Mr Cameron says corruption is "the root of so many of the world's problems".
  He also described it as "an enemy of progress".
  "It destroys jobs and holds back economic growth, traps the poorest in desperate poverty, and undermines our security by pushing people towards extremist groups," he added.
  "The battle against corruption will not be won overnight. It will take time, courage and determination to deliver the reforms that are necessary. But we cannot hope to solve the major global challenges we face without tackling the exploitation, fraud and dishonesty at their heart.
  "For too long there has been a taboo about tackling this issue head-on. The summit will change that. Together we will push the fight against corruption to the top of the international agenda where it belongs."
  Among the world leaders attending the summit are presidents Ashraf Ghani of Afghanistan, Juan Manuel Santos of Colombia and Muhammadu Buhari of Nigeria, and Norwegian prime minister Erna Solberg.
  Russia is to be represented by deputy foreign minister Oleg Syromolotov.
  Panellists are expected to include World Bank president Jim Yong Kim and International Monetary Fund's managing director Christine Lagarde.
  Under the prime minister's plans, leaders at the summit would pledge to expose corruption and pursue and punish those who perpetrate, facilitate or are complicit in it.
  Campaigners have also called for a crackdown on tax havens linked to the United Kingdom. The recent Panama Papers leak showed how some wealthy people use offshore firms to evade tax and avoid sanctions.
  A Downing Street spokesman said: "We are in discussions with the Overseas Territories and Crown dependencies with major financial centres about their attendance, and expect a number to join the summit."
  Robert Barrington, of anti-corruption campaigners Transparency International, said: "The prime minister is creating a platform for governments that are serious about fighting corruption to make really significant changes and set the agenda for a generation to come.
  "What is key now is that other governments are persuaded to sign up to ambitious targets and that the UK government does not give in to the usual last minute attempts by less committed countries to water down the summit's ambitions".
target: Prime Minister David Cameron has said he wants to put tackling corruption at the "top of the international agenda" ahead of a London summit on the issue.